I managed to add all my local contacts and send & receive BBM. However, if the local contacts go roaming, I could not connect with them through BBM anymore. The problem solved once I upgraded to new BBM Version 5.

Unfortunately, I still can not add international contacts. The funny thing about it is that my requests to add contacts were received by my friends and accepted by them. In fact, they received my BBM! When they replied, I did not receive the BBM! In addition, in my contact list, their names still "Pending (Awaiting Authorisation)".